It is the French version of the English black pudding, although in Spanish "black pudding" is interpreted as a chocolate dessert. See ingles/pudding .
They are not words of Spanish language but French. They literally mean black pudding. It is actually a sausage with blood of pork, pieces of meat, fat and other elements. In Colombia we say Wallachian, blood sausage or black tubing.
BOUDIN NOIR: Charcuterie defibrinated fibre-based product and pork fat, seasoned and introduced into a gut.